In wireless communication systems, RRM is generally responsible for utilizing the air interface resources. RRM is used to guarantee quality of service (QoS), to provide efficient use of the radio resources, and to increase system capacity. RRM consists of admission control, handover, power control, and congestion control functionalities. Admission control can be divided into user admission control and call admission control (CAC). User admission control accepts or rejects the radio resource control (RRC) connection requested by a wireless transmit/receive unit (WTRU). Call admission control accepts or rejects a request to establish or modify a radio access bearer (RAB) in the radio access network (RAN). Call admission control is located in the controlling radio network controller (C-RNC).
There are two dynamic channel allocation (DCA) functions, slow DCA and fast DCA (S-DCA, F-DCA). The S-DCA allocates the radio resources to cells while the F-DCA allocates the radio resources to bearer service. Two F-DCA functions, which could be in the form of algorithms, are executed by RRM at steady state operation: one for background interference reduction and one for an escape mechanism.
The F-DCA escape mechanism is used to solve a link problem of a user. It is used as an escape mechanism for a specific user (or part of user services) or a base station that experiences high interference or that cannot satisfy QoS by reassigning the radio resources to an existing radio bearer. The F-DCA escape mechanism runs in a cell for all WTRUs in steady state with real time (RT) services. It does not apply to non-real time (NRT) services.
Only one F-DCA function is preferably run at a given time in a C-RNC, because the output of one function may affect the decision of another function. If more than one of these functions are triggered at exactly the same time, the priority of these functions is such that the escape mechanism runs first, CAC runs second, and the background interference reduction algorithm runs last.
It is desirable to provide an improved escape mechanism, which satisfies the foregoing requirements.